Antibacterial synergy between a phage endolysin and citric acid against the Gram-negative kiwifruit pathogen <i>Pseudomonas syringae</i> pv. <i>actinidiae</i>
Hazel M Sisson, Robert D. Fagerlund, Simon A. Jackson, Yves Briers, Suzanne L. Warring, Peter C. Fineran
Abstract
below detection. We show that citric acid drives the destabilization of the outer membrane via acidification and sequestration of divalent cations from the lipopolysaccharide, which is followed by the degradation of the peptidoglycan by the endolysin. Scanning electron microscopy revealed clear morphological differences, indicating cell lysis following the endolysin-citric acid treatment. These results show the potential for citric acid-endolysin combinations as a possible antimicrobial approach in agricultural applications. IMPORTANCE: below the limit of detection. The use of citric acid as a synergistic agent with endolysins has not been extensively studied and has never been evaluated against a plant pathogen. We determined that the synergy involved a combination of the chelation activity of citric acid, acidic pH, and the specific activity of the ΦPsa374 endolysin. Our study highlights an exciting opportunity for alternative antimicrobials in agriculture.